One difference with the pro series is the port for the electric starter. I bought a couple pro series this year and in hindsight I wish it didn’t have the port. It makes the slide out ash door very large and therefore a much larger opening to seal. I used the port initially but as I progressed down the kamado path eventually added a temp controller and kick ash basket. I find it easier and more convenient to light just using alcohol soaked cotton balls, the controller would have fit the B series better (without customization) and I had to remove the starter grate/cover for the kick ash basket so it's no longer an option. Meanwhile, I get air leaks around the large slide out gasket. I've actually been considering how I might be able to adapt it to the B version ash tray and seal off the rest of the opening. Anyone with a B want to trade up to a Pro-S?